Patient-specific convertible guides

ABSTRACT

A method of intraoperatively selecting between a partial knee arthroplasty and total knee arthroplasty includes mounting a patient-specific three-dimensional surface of a convertible patient-specific guide in a unique position mating to a corresponding surface of a distal femoral bone. The convertible patient-specific guide includes an anterior portion and a distal portion a patellofemoral guide. One of a total knee arthroplasty and a partial knee arthroplasty is selected intraoperatively. If total knee arthroplasty is selected, first and second covers are removed from corresponding first and second distal guiding bore. First and second distal pins through the first and second distal guiding bores are registered on the bone. If partial knee arthroplasty is selected, the anterior portion is severed and removed along a frangible groove and the distal portion is used as a patellofemoral guide.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 13/097,145 filed on Apr. 29, 2011. The disclosure of the above application is incorporated herein by reference.

FIELD

The present teachings relate to patient-specific guides for orthopedic surgery and in particular to patient-specific guides that are convertible to accommodate intraoperative changes of a preoperative surgical plan for a patient.

INTRODUCTION

The present teachings relate to devices and methods for enabling the surgeon to change a preoperative surgical plan for a specific patient intraoperatively from a first surgical procedure to a second surgical procedure without requiring separate patient-specific guides that are individually dedicated to each procedure. For example, the preoperative plan for the patient may be designed for a partial knee arthroplasty, but intraoperatively, the surgeon may make a determination to perform a total knee arthroplasty. The present disclosure provides various exemplary guides for allowing the surgeon to convert from one surgical procedure to another intraoperatively with efficiency, ease and cost effectiveness.

SUMMARY

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

The present teachings provide a convertible patient-specific guide for use in arthroplasty. The convertible guide has a body having a patient-specific three-dimensional undersurface closely mateable in only one position with a corresponding joint surface of a specific patient. The convertible guide includes patient-specific guiding formations extending from the body and configured for guiding both a total arthroplasty of the joint and a partial arthroplasty of the joint, such that the arthroplasty to be performed is intraoperatively changeable.

The present teachings also provide a convertible patient-specific guide that includes a body having a patient-specific three-dimensional undersurface closely mateable in only one position with a corresponding femoral knee joint surface of a specific patient. The convertible patient-specific guide includes patient-specific guiding formations extending from the body and configured for guiding a total knee arthroplasty of the joint. The convertible patient-specific guide further includes a connector extending from the body. The connector can be coupled with a patient-specific unicondylar knee guide for intraoperatively converting a unicondylar partial knee arthroplasty to a total knee arthroplasty.

The present teachings provide a method of intraoperatively selecting between a partial knee arthroplasty and total knee arthroplasty. The method includes mounting a patient-specific three-dimensional surface of a patient-specific guide in a unique position mating to a corresponding surface of a distal femoral bone. The patient-specific guide includes an anterior portion and a distal portion including a patellofemoral guide portion. The method includes selecting one of a total knee arthroplasty and a partial knee arthroplasty. If total knee arthroplasty is selected, first and second covers are removed from corresponding first and second distal guiding bores and first and second distal pins are registered through the first and second distal guiding bores. If partial knee arthroplasty is selected, the anterior portion is removed along a frangible groove and the patellofemoral guide portion for partial knee arthroplasty.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is an environmental view of a patient-specific convertible guide selectively usable either for a total knee arthroplasty or a patellofemoral procedure as determined intraoperatively by the surgeon according to the present teachings;

FIG. 1A is a perspective view of an exemplary patellofemoral implant;

FIG. 2 is a plan view of a patient-specific patellofemoral guide according to the present teachings;

FIG. 3 is an environmental view of a patient-specific convertible guide with an anterior removable section, such that the convertible guide is selectively usable either for a total knee arthroplasty or a patellofemoral procedure as determined intraoperatively by the surgeon according to the present teachings;

FIG. 3A is a detail of the patient-specific convertible guide of FIG. 3;

FIG. 4 is the patient-specific convertible guide of FIG. 3 with the anterior section removed and shown with a resection guide according to the present teachings;

FIG. 5 is an environmental view of a patient-specific guide for partial knee arthroplasty shown with a convertible guide for total knee arthroplasty according to the present teachings;

FIG. 6A is a perspective view of a patient-specific guide for partial knee arthroplasty according to the present teachings;

FIG. 6B is another perspective view of the patient-specific guide for partial knee arthroplasty of FIG. 6A;

FIG. 6C is a perspective view of a drill template for the patient-specific guide for partial knee arthroplasty of FIG. 6A according to the present teachings;

FIG. 6D is an environmental view of a femoral bone with a resection block supported in holes drilled in the bone using the drill template of FIG. 6C according to the present teachings;

FIG. 7 is a bottom plan view of a patient-specific femoral bone model according to the present teachings; and

FIG. 8 is an elevated view of a patient-specific tibial bone model according to the present teachings.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

Exemplary embodiments will now be described more fully with reference to the accompanying drawings.

The present teachings generally provide various patient-specific or custom guides and/or other instruments and devices for total and/or partial arthroplasty including unicondylar knee arthroplasty and patellofemoral compartment arthroplasty. More specifically, the present teachings provide various customized and patient-specific guides and other devices that enable the surgeon to change a preoperative surgical plan for a specific patient intraoperatively from a first surgical procedure to a second surgical procedure without requiring separate patient-specific guides dedicated to each procedure. For example, preoperatively, a partial knee arthroplasty (PKA) may have been contemplated for a specific patient, but intraoperatively observed conditions may lead the surgeon to perform a total knee arthroplasty (TKA) instead.

The present teachings provide various exemplary guides, devices and methods for allowing the surgeon to convert from one surgical procedure to another intraoperatively while maintaining the benefit of a preoperative plan and the use of patient-specific guides. In some embodiments, for example, a single patient-specific guide can be a dual purpose/dual function guide that can provide alignment guidance for both TKA and PKA procedures. In some embodiments, a single patient-specific guide can be convertible from one procedure to another. Unless there is a need to distinguish between particular embodiments, patient-specific guides designed for dual surgical procedures or convertible from one surgical procedure to another intraoperatively will be referenced as “convertible” guides. Patient-specific convertible guides are described below in further detail, although non-custom convertible guides can also be used.

The patient-specific convertible guides and other associated instruments and devices can be used either with patient-specific or with conventional/standard (i.e., non-custom) femoral or tibial implant components. Generally, patient-specific devices can be designed preoperatively using computer-assisted image methods based on three-dimensional images of the patient's knee anatomy reconstructed from MRI, CT, ultrasound, X-ray, or other three- or two-dimensional medical scans of the patient's anatomy and in some cases complemented with digital photography methods and/or anthropometry databases. Various CAD programs and/or software can be utilized for three-dimensional image reconstruction, such as software commercially available, for example, by Materialise USA, Plymouth, Mich.

In the preoperative planning stage for a joint replacement or revision procedure, such as, for example, total knee arthroplasty (TKA) or partial knee arthroplasty (PKA), or patellofemoral compartment (PFR) arthroplasty, imaging data of the relevant anatomy of a patient can be obtained at a medical facility or doctor's office, using one of medical imaging methods described above. The imaging data can include, for example, various medical scans of a hip, knee, ankle or other joint or relevant portion of the patient's anatomy, as needed for joint modeling, mechanical/alignment axis determination or for other alignment purposes. The imaging data obtained and other associated information can be used to construct a three-dimensional computer image of the joint or other portion of the anatomy of the patient. An initial preoperative plan can be prepared for the patient in image space and can include bone or joint preparation, planning for resections, milling, reaming, broaching, implant selection and fitting, as well as designing patient-specific guides, templates, tools and alignment methods for the surgical procedure.

In the context of the present teachings, patient-specific guides and implants are generally configured to match the anatomy of a specific patient and are generally formed using computer modeling based on the patient's reconstructed three-dimensional anatomic image. The patient-specific guides have an engagement surface that is made to conformingly contact and match a three-dimensional image/model of the patient's bone surface (with or without cartilage or other soft tissue), by the computer methods discussed above. In this respect, a patient-specific guide can nestingly mate with the corresponding bone surface (with or without articular cartilage) of the specific patient in only one position. The patient-specific alignment guides can include custom-made (patient-specific) guiding formations, such as, for example, guiding bores or cannulated guiding posts or cannulated guiding extensions or receptacles that can be used for supporting or guiding other instruments, such as drill guides, reamers, cutters, cutting guides and cutting blocks or for inserting pins or other fasteners according to a surgeon-approved pre-operative plan.

The customization of the guiding formations is designed during the preoperative plan to provide templates for guiding cutting tools to perform the planned drilling, resections or other surface preparation according to the preoperative plan. For example, the guiding formations can provide spatial orientation and positions for drilling of holes to insert pins or other supporting connectors for mounting the corresponding cutting tools for the preparation of the bone. The patient-specific guides can be used in minimally invasive surgery, and also in surgery with multiple minimally-invasive incisions. Various alignment guides and pre-operative planning procedures are disclosed in commonly assigned and co-pending U.S. patent application Ser. No. 11/756,057, filed on May 31, 2007, U.S. patent application Ser. No. 12/211,407, filed Sep. 16, 2008; U.S. patent application Ser. No. 11/971,390, filed on Jan. 9, 2008, U.S. patent application Ser. No. 11/363,548, filed on Feb. 27, 2006; U.S. patent application Ser. No. 12/025,414, filed Feb. 4, 2008, U.S. patent application Ser. No. 12/571,969, filed Oct. 1, 2009, and U.S. patent application Ser. No. 12/955,361, filed Nov. 29, 2010. The disclosures of the above applications are incorporated herein by reference.

The outcome of the initial fitting is an initial surgical plan that can be printed or provided in electronic form with corresponding viewing software. The initial surgical plan can be surgeon-specific, when using surgeon-specific alignment protocols. The initial surgical plan, in a computer file form associated with interactive software, can be sent or otherwise provided over the internet or other cloud/web type of communication to the surgeon, or other medical practitioner, for review. The surgeon can incrementally manipulate the position of images of the implant components in an interactive image of the joint. Additionally, the surgeon can select or modify resection planes, types of implants and orientation and position of implant insertion. After the surgeon modifies and/or approves the surgical plan, the surgeon can send or electronically communicate or save in an internet space or dedicated server the final, approved preoperative plan that can be accessed by the manufacturer. Patient-specific guides and other tools for the approved preoperative plan can be manufactured and included with the selected implants and other instruments or devices in a kit for the specific patient, specific procedure and specific surgeon. In addition, patient-specific physical models of the corresponding bone portions can be prepared for physical visualization and trial testing of the bone, as discussed below. The various patient-specific guides discussed herein can be made of any biocompatible material, including metal or plastic. Generally, the patient-specific guides are disposable and made of lightweight materials, including polymers.

Referring to FIG. 1, an exemplary dual purpose, (“convertible” for short) patient-specific guide 100 is shown mounted on the corresponding patient's distal femur 80. The convertible guide 100 includes a light-weight body 102 having an inner or anatomy engaging surface 104 that is designed during the preoperative plan of the patient to be patient-specific, i.e., to nestingly mate with the patient's joint surface, such as portions of the anterior and distal surfaces of the patient's femur 80 (with or without articular cartilage) in only one position, as determined by the preoperative plan. The convertible guide 100 can include a visualization window/opening 106 and first and second distal guiding formations 108 defining distal guiding bores 110 for guiding corresponding distal alignment pins (not shown). The convertible guide 100 can also include first and second anterior guiding formations 112 defining anterior guiding bores 114 for guiding corresponding anterior alignment pins (not shown). The distal and anterior guiding formations 108, 112 are designed to have orientations and positions for guiding pins or other connecting members on which to support various cutting instruments to perform the resections determined in a preoperative plan for an optional total knee arthroplasty. A fifth patellofemoral guiding formation 116 having a patellofemoral guiding bore 118 is also provided on the convertible guide 100 for guiding an optional partial knee replacement, such as a patellofemoral replacement in which a patellofemoral replacement system is used, such as, for example, the Vanguard® PFR Partial Knee, commercially available from Biomet Manufacturing Corp., Warsaw, Ind. An exemplary PFR implant 50 having a stem 52 for attachment to the patellofemoral compartment of the bone is illustrated in FIG. 1A. The various guiding formations can be in the form of tubular structural elements, such as, for example, conical portions or cylindrical portions with cut-outs or windows, and such that the guiding formations can provide guiding support for drilling holes in the bone with reduced weight and improved visibility.

More specifically, the patient-specific convertible guide 100 is designed during the preoperative plan for the specific patient to guide a first type of arthroplasty selected by the surgeon, but is also capable to be used for and guide a second type of arthroplasty, when the surgeon determines intraoperatively that the second type is indicated based on intraoperative conditions or other intraoperative considerations. In the exemplary embodiment of FIG. 1, the convertible guide 100 can be selectively used either for total knee arthroplasty (TKA) or for a partial knee arthroplasty, such as a patellofemoral (PFR) arthroplasty that replaces only the patellofemoral compartment of the knee joint. Accordingly, the convertible guide 100 can be used intraoperatively for total knee arthroplasty or for partial patellofemoral arthroplasty based on an intraoperative determination by the doctor.

Further, the convertible guide 100 can be used for a patellofemoral arthroplasty even though the preoperative plan calls for patellofemoral arthroplasty and no intraoperative change in plan is envisioned, i.e., when no change from a patellofemoral to total knee arthroplasty is contemplated. In such case, the patient-specific convertible guide 100 can still provide improved alignment guidance that requires fewer intraoperative adjustments than conventional trialing and other patellofemoral (PFR) guides, as described below.

The convertible guide 100 can be attached to the femur using anterior pins through the anterior bores 114. The distal guiding bores 110 can be capped or otherwise obstructed with removable, severable, frangible/breakable covers 120, such that no distal holes are drilled through the distal guiding bores 110, unless the surgeon opts for a total knee arthroplasty procedure, in which case the covers 120 are removed or snapped off or twisted off. A patellofemoral pin hole 122 can be drilled into the femur through the patellofemoral guiding bore 118.

The convertible guide 100 can be removed and a PFR-specific guide 150 can be guided by and pinned on to the femoral bone using the patellofemoral hole 122, as shown in FIG. 2. The PFR guide 150 can be patient-specific and also designed based on the preoperative plan for the specific patient. The PFR guide 150 can include a body 152 having a bone-engagement undersurface 154 that can nestingly mate and conform to the three-dimensional patellofemoral compartment of the patient's distal femur 80. The PFR guide 150 can include two distal guiding formations 158 having distal guiding bores 160 corresponding to the distal guiding bores 110 of the convertible guide 100 and a patellofemoral guiding formation 166 with a patellofemoral bore 168 corresponding to the patellofemoral formation 116 and patellofemoral bore 168 of the convertible guide 100 of FIG. 1. The distal guiding bores 160 can be covered with covers 120, which can be removed, if a TKA procedure is intraoperatively selected by the surgeon instead of the PFR procedure. The PFR guide 150 can also include a supporting structure 170 having first and second slots, openings or other connecting structural features 172 for removably connecting and aligning a femoral resection block 180 (shown in FIG. 4) to the PFR guide 150. In the embodiment illustrated in FIG. 4, the femoral resection block 180 includes first and second legs 182, 184 that can be slidably inserted into the corresponding slots 172 of the PFR guide 150. The femoral resection block 180 can also include a cutting guide 184 for guiding a cutting instrument, such as a blade, to perform an anterior resection. The cutting guide 184 can have a curved or J-shaped profile for wrapping around the medial side of the femur 80 to provide access for the anterior resection. The femoral resection block 180 can also include an aperture 186 for optionally connecting an anterior stylus (not shown), for confirming sizing.

The patient-specific convertible guide 100 and the patient-specific PFR guide 150 are prepared during the preoperative plan so that both are shipped to the surgeon and can be used together. For example, the convertible guide 100 provides all the functions of a patient-specific TKA alignment guide and also includes the additional feature of a PFR guiding formation 116 for drilling the PFR drill hole 122. In this respect, the convertible guide 100 can provide alignment guidance for location or reference pins for use either in a TKA procedure or a partial knee arthroplasty (PKA), such as a PFR procedure. When a TKA procedure is intraoperatively selected, alignment or location pins are placed into the bone through the anterior and distal guiding bores 114, 110 for supporting a distal resection guide, a four-in one cutting block or other cutting block for an anterior resection, chamfer resections, etc., as described in commonly assigned and co-pending U.S. patent application Ser. No. 11/756,057, filed on May 31, 2007, incorporated herein by reference.

Referring to FIGS. 3-5, in some embodiments, the functions of convertible guide 100 and PFR guide 150 are incorporated in a single patient-specific convertible guide 200. The same reference numerals are used to denote common elements between the convertible guide 200 and guides 100 and 150. The convertible guide 200 is a frangible, breakable or severable guide with a fracture line or groove or other separator element 230. The separator element 230 facilitates separating a first or anterior portion 202 of the convertible guide 200 from a second portion 250, which, when severed or separated from the first portion 202, defines a standalone, complete guide that is interchangeable with the PFR guide 150 (marked herein with the same numeral numbers as the PFR guide 150). The first portion 202 includes a patient-specific mating undersurface 204 that can be mounted in only one position and mate in a three-dimensional way with the patient's corresponding anatomy. The first portion 202 can include the anterior guiding formations 112 and corresponding bores 114 and the window 106.

The convertible guide 200 provides the surgeon with various options for intraoperative use. For example, in one option, the covers 120 can be removed from the distal guiding bores 160, and the convertible guide 200 can be used as a patient-specific TKA guide providing alignment references and registration for anterior pins through the anterior guiding bores 114 and for distal pins through the distal guiding bores 160. In another option, the convertible guide 200 can be used in a PFR procedure instead of the combination of guides 100 and 150 of FIGS. 1 and 2 discussed above. In this respect, the PFR portion 250/150 can be snapped off either before or after registration to the bone of the patient. For example, the entire convertible guide 200 can be first uniquely mated to the patient's femoral bone 80 and pinned on the femur 80. Then, the first portion 202 can be snapped off and removed, leaving the second portion 250 or PFR guide 150 mounted on the femoral bone 80 to be used with the anterior resection block 180 to perform the anterior resection, as discussed above in reference to FIG. 4. Another option is to snap off the anterior portion 202 before the convertible guide 200 is mounted on the femoral bone 80, such that only the PFR portion 250 or PFR guide 150 is mounted on the femoral bone 80, using the patient-specific undersurface 154 for registration, in view of the fact that the undersurface 154 is designed preoperatively to mate with the corresponding anatomy of the patient in only one position, as discussed above.

Referring to FIG. 5, a patient-specific convertible guide 400 for converting partial (unilateral or unicondylar) knee arthroplasty to total knee arthroplasty is illustrated. The convertible guide 400 can be used with a partial or unilateral or unicondylar femoral guide 300, which can be patient-specific (customized for the patient) or not (standard, non-custom), as shown in FIGS. 6A-6D. The unilateral knee guide 300 illustrated in FIGS. 5, 6A and 6B is patient-specific and includes a body 302 with a three-dimensional patient-specific undersurface 304 designed during the preoperative plan to conform to unilaterally, i.e., to only one of the medial and lateral surfaces/femoral condyles of the femoral bone 80 of the patient in only one position. The body 302 and the undersurface 304 can extend from a distal portion 312 over one of the lateral or medial femoral condyles to an anterior portion 314. The unilateral knee guide 300 can be marked with the name of the patient and the corresponding knee and condyle, such as “RIGHT/MEDIAL”, for example, for convenient preoperative and intraoperative identification. A guiding formation 308 extends generally from the distal portion 312. The guiding formation 308 defines an elongated slot 310 with a tapered inner peripheral wall 306. A drill template 320 can be provided for guiding a drill to form one or more holes in the bone as determined during the preoperative plan. An exemplary drill template 320 is illustrated in FIG. 6C in the form of an insert with a tapered peripheral wall 322 that can mate with the inner peripheral wall 306 of the elongated slot 310. The drill template 320 can include a number of guiding holes 324 at a patient-specific location and configuration relative to the unilateral knee guide 300. Two guiding holes 324 are illustrated in FIG. 6C. Depending on the procedure, the surgeon can determine intraoperatively whether to drill corresponding holes 86 in the bone for supporting a resection block 350, as shown in FIG. 6D. In some embodiments, several patient-specific drill templates 320 having different configurations of guiding holes 324 can be provided. The drill templates 320 can be, for example, metallic for added stability, or plastic with sufficient thickness to provide stability.

Intraoperatively, the surgeon can mount the unilateral knee guide 300 on the specified knee and condyle of the patient in a unique position based on the preoperative plan for the patient. If the surgeon determines to proceed with the partial knee procedure, then the drill template 320 can be fitted over the elongated slot 310 and holes 86 for guiding pins can be drilled into the bone 80. The unilateral knee guide 300 can then be removed, and the holes 86 can be used to mount rods or pins 352 of a cutting instrument, such as the resection block 350 illustrated in FIG. 6D, in a position predetermined by the holes 86 drilled in the bone. The resection block 350 is then positioned for performing a resection along a plane 88 for excising the posterior facet of the femoral condyle at a location and orientation determined during the preoperative plan for the patient. The surgical technique can then follow standard procedures, such as, for example, the surgical technique associated with the Oxford® Partial Knee, which is commercially available by Biomet Manufacturing Corp., Warsaw, Ind., and described at Biomet's website.

Alternatively, the surgeon may determine intraoperatively that a total knee arthroplasty (TKA) is indicated instead of the initially planned partial knee arthroplasty (PKA). The convertible guide 400 can then be placed over the already mounted partial knee guide 300 to provide patient-specific registration for a total knee arthroplasty based on the preoperative plan for the patient. The convertible guide 400 is a lightweight guide already sized and shaped for the specific patient in conjunction with the partial knee guide 300. The convertible guide 400 is designed to mate and align with the patient's femoral bone 80 when mounted over the partial knee guide 300 based on the preoperative plan for the patient and in anticipation of a possibility that TKA may be intraoperatively selected instead of the initially planned PKA.

Referring to FIG. 5, in some embodiments, the convertible guide 400 can form a frame of interconnected elongated members including lateral and medial elongated members 402, 404 for the corresponding femoral condyles, an anterior elongated member 406 and a distal elongated member 408. The interconnected elongated members 402, 404, 406, 408 can generally follow and conform the patient's three-dimensional geometry, while their corresponding undersurfaces 403, 405, 407, 409, spatial dimensions and orientations are patient-specific and designed for the anatomy of the specific patient during the preoperative plan. The convertible guide 400 can include guiding formations for TKA pin registration, including anterior guiding formations 410 at connecting portions between the anterior member 406 and the lateral and medial members 402, 404, and distal guiding formations 412 at connecting portions between the distal member 406 and the lateral and medial members 402, 404. The elongated member that is designed to engage the partial knee guide 300, i.e., medial member 404 in the illustration of FIG. 5, includes a connector or extension 414 having a tapered wall 416 that can be received into the elongated slot 310 of the partial knee guide 300 and mate with the tapered inner wall 306 of the slot 310. The corresponding medial distal guiding formation 412 is formed on the extension 414.

The frame structure of the elongated members 402, 404, 406, 408 provides a lightweight and inexpensive addition to the patient-specific kit of a patellofemoral procedure, although a different structure or shape, such as the structure of the patient-specific guides for total knee arthroplasty can be used with the addition of a connector 414.

Referring to FIGS. 7 and 8, physical (plastic, for example) bone models created as part of the preoperative plan can also be provided to the surgeon in a kit with the patient-specific convertible guides and PFR or PKA guides describe above. The physical bone models have outer three-dimensional surfaces replicating the actual outer bone surfaces of the specific patient and can help the surgeon mount the provided guides thereon and/or visualize the resections and other procedures before mounting the guides on the actual bone of the patient during the operation. These physical bone models can be provided with a support structure that can receive a support element, such as a rod, so that the surgeon can support the physical bone model without directly holding it, thereby providing a full three-dimensional view of the physical bone model. As an example, FIG. 7 illustrates an underside plan view of a physical bone model 500 of the distal femur of a specific patient. The physical bone model 500 has an outer three-dimensional surface 510 that replicates the outer surface of the distal femur of the patient. The support structure includes a central hub 506 supported by a number of arms 504 extending from an inner wall 502 of a hollow underside surface 503 of the bone model 500. The hub 506 can have a blind bore 508 for receiving a holding member, such as the holding member 560 shown in FIG. 8, for holding the bone model with the hollow underside surface 503 facing downwards.

FIG. 8 illustrates a physical bone model 550 for a proximal tibial bone of the specific patient. The physical bone model 550 has an outer three-dimensional surface 554 that replicates the outer surface of the proximal tibia of the patient. The bone model 550 can include a blind bore 552 for receiving a holding member 560 to hold the physical bone for visualization of the resection and other alignment procedures determined during the preoperative plan for the patient. The holding member 560 can be a rod, a bar or other holding structure. The holding member 560 can be held by hand or supported on an appropriate base member 562 on a table or other surface.

The various patient-specific guides, other tools and physical bone models described herein can be manufactured by various stereolithography methods, selective laser sintering, fused deposition modeling or other rapid prototyping methods. In some embodiments, computer instructions of tool paths for machining the patient-specific guides and/or implants can be generated and stored in a tool path data file. The tool path data can be provided as input to a CNC mill or other automated machining system.

The guides and other tools can be made of polymer, ceramic, metal or other suitable material depending on the use, and sterilized as needed. The sterilized tools and bone models can be shipped to the surgeon or medical facility in a kit for a specific patient and surgeon to be used during the surgical procedure.

The various embodiments of patient-specific convertible guides, patellofemoral guides, unilateral/unicondylar guides, drill templates and other instruments can be provided in various combinations to the surgeon and used to facilitate the conversion of a patient-specific preoperative plan from one procedure to another intraoperatively, while retaining the patient-specific guidance provided by the preoperative plan. In this respect, the present teachings integrate preoperatively two different surgical procedures so that either one can be selected intraoperatively as a patient-specific procedure without excessive duplication.

Example embodiments are provided so that this disclosure is thorough, and fully conveys the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure.

It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Accordingly, individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 

What is claimed is:
 1. A method of intraoperatively selecting between a partial knee arthroplasty and total knee arthroplasty comprising: mounting a patient-specific three-dimensional surface of a convertible patient-specific guide in a unique position mating to a corresponding surface of a distal femoral bone, the patient-specific guide including an anterior portion and a distal portion with a patellofemoral guide portion; selecting intraoperatively one of a total knee arthroplasty and a partial knee arthroplasty; if total knee arthroplasty is selected, removing first and second covers from corresponding first and second distal guiding bores and registering first and second distal pins through the first and second distal guiding bores; and if partial knee arthroplasty is selected, removing the anterior portion along a frangible groove and using the patellofemoral guide portion.
 2. The method of claim 1, further comprising registering first and second anterior pins through first and second anterior guiding bores of the anterior portion.
 3. The method of claim 1, further comprising supporting a femoral resection block on the patellofemoral guide portion.
 4. The method of claim 3, further comprising slidably inserting first and second legs of the femoral resection block into first and second slots of the patellofemoral guide portion.
 5. The method of claim 1, wherein the frangible groove has reduced thickness relative to the anterior and distal portions.
 6. A method of intraoperatively selecting between a partial knee arthroplasty and total knee arthroplasty comprising: providing a convertible patient-specific guide including an anterior portion and a distal portion having a score line of reduced thickness therebetween, the patient-specific guide having a patient-specific three-dimensional undersurface designed preoperatively based on images of a patient's knee joint, the patient-specific three-dimensional undersurface closely mateable in only one position relative to the knee such that the patient-specific three-dimensional undersurface nestingly fits about and within surface portions of a corresponding surface of the knee joint of the patient in a single position; selecting intraoperatively one of a total knee arthroplasty and a partial knee arthroplasty; if total knee arthroplasty is selected, mounting the convertible patient-specific guide on the distal femoral bone; and if partial knee arthroplasty is selected, severing and removing the anterior portion along the score line and using the distal portion as a patellofemoral guide.
 7. The method of claim 6, wherein the anterior portion is severed and removed before mounting the convertible patient-specific guide on the knee joint.
 8. The method of claim 6, wherein the anterior portion is severed and removed after mounting the convertible patient-specific guide on the knee joint.
 9. The method of claim 6, further comprising registering anterior and distal pins through corresponding anterior and distal guiding bores and removing covers from the distal guiding bores.
 10. The method of claim 6, further comprising: mounting an anterior femoral resection block on the distal portion; and making an anterior femoral resection.
 11. The method of claim 10, wherein mounting an anterior femoral resection block on the distal portion includes sliding first and second legs of the anterior femoral resection block into corresponding first and second slots of a support extending from the distal portion.
 12. A method of intraoperatively selecting between a partial knee arthroplasty and total knee arthroplasty comprising: providing a convertible patient-specific guide having a first body portion and a second body portion, wherein: the first body portion has a first patient-specific three-dimensional undersurface custom-made to match an anterior femoral knee joint surface of a specific patient such that the first patient-specific three dimensional-undersurface nestingly fits about and within surface portions of the joint surface in a first position relative to the knee joint; the second body portion has a second patient-specific three-dimensional undersurface custom-made to match a distal femoral surface of the patient such that the second patient-specific three dimensional-undersurface nestingly fits about and within surface portions of the joint surface in a second position relative to the knee joint; the first and second patient-specific three-dimensional undersurfaces are constructed from images of the patient's knee joint; and the second body portion is connected to the first body portion along a frangible line of reduced thickness relative to the first and second body portions; selecting intraoperatively one of a total knee arthroplasty and a partial knee arthroplasty; if total knee arthroplasty is selected, mounting the convertible patient-specific guide on the distal femoral bone; and if partial knee arthroplasty is selected, severing and removing the first body portion along the frangible line and using the second portion as a patellofemoral guide.
 13. The method of claim 12, wherein the first body portion is severed and removed before mounting the convertible patient-specific guide on the knee joint.
 14. The method of claim 12, wherein the first body portion is severed and removed after mounting the convertible patient-specific guide on the knee joint.
 15. The method of claim 12, further comprising registering anterior and distal pins through corresponding anterior and distal guiding bores and removing covers from the distal guiding bores.
 16. The method of claim 12, further comprising: mounting an anterior femoral resection block on the second body portion; and making an anterior femoral resection.
 17. The method of claim 16, wherein mounting an anterior femoral resection block on the second body portion includes sliding first and second legs of the anterior femoral resection block into corresponding first and second slots of a support extending from the second body portion.
 18. The method of claim 12, wherein the frangible line is a score line.
 19. The method of claim 12, wherein the frangible line is a groove.
 20. The method of claim 12, wherein the frangible line is designed preoperatively from the images of the knee joint to correlate the frangible line to a structure of the patient's knee. 